In recent years, it is desirable for even an image sensor with high resolution to pick up a high-quality image with low resolution.
For example, a function of taking moving images by a digital still camera and, in contrast, a function of picking up a still image by a camcorder have become common
Moreover, in these electronic units, in many cases, a view finder for checking a picture is included; however, the resolution of the view finder is lower than an image to be picked up.
Further, some of digital still cameras, cellular phones, and the like have a function of improving a frame rate during low-resolution image pickup to pick up images of high-speed movement which are invisible in related art.
As described above, it is desirable for one image sensor to support both of high-resolution still images at a low frame rate and relatively-low-resolution moving images at a high frame rate.
On the other hand, there is proposed a CMOS (Complementary Metal Oxide Semiconductor) image sensor supporting all-pixel readout mode in which signals are read from all pixels and selective readout mode in which signals are intermittently read by skipping a row or a column.
In this CMOS image sensor, all-pixel readout mode is used to take a high-resolution still image, and selective readout mode is used to pick up low-resolution moving images or images at a high frame rate.
PTL 1 describes a CMOS image sensor improving image quality in the case where moving images are picked up in selective readout mode.
In this method, the position of a readout pixel is changed from one frame to another to vary sampling phase and frequency, thereby reducing moire.